1. Field of the Invention
This invention relates to an electrical contact alloy for use in sealed electromagnetic relays, and more particularly, to an electrical contact alloy which aids in preventing the deposition of carbon residue on the surfaces of the contact.
2. Description of the Related Art
Generally, in sealed solenoid relays or other electrical devices which are fabricated by assembling various component parts into a housing, low-boiling hydrocarbon organic gases evolved from resin parts, such as ethane, methane, benzene and xylene, tend to be trapped and collect within the housing. These organic gases are oxidized and decomposed by the arc and mechanical energies associated with the switching actions of the electrical contact, and the resulting deposits of carbon on the surface of the contact points cause poor contact. This phenomenon is particularly pronounced at higher ambient temperatures. Therefore, degassing of the plastic parts prior to assembly is the common practice.
However, the organic gases included in the resin parts cannot be completely removed by such a degassing operation. Thus, the gradual deposition of carbon on the contact surfaces and the consequent poor contact have been unavoidable. Furthermore, for sealed electromagnetic relays, which are used for low-level signal switching, expensive materials such as gold (Au) metal and Au alloys have previously been used as contact materials for improved reliability. However, since such electrical contacts tend to develop poor contact in the presence of even trace amounts of carbon, the reliability of these relays has not been sufficient.